Cisplatin and gemcitabine as the first line therapy in metastatic triple negative breast cancer.

No standard first-line treatment exists for patients with metastatic triple-negative breast cancer (mTNBC). In this single-arm, phase II study (NCT00601159), we evaluated the efficacy and tolerability of cisplatin and gemcitabine (GP) as the first-line therapy in mTNBC. Eligible women were those who had measurable disease with no prior chemotherapy for mTNBC. All patients received 21-day-cycle of cisplatin 25 mg/m(2) on days 1-3 and gemcitabine 1,000 mg/m(2) on days 1 and 8. Treatment was continued until disease progression, unacceptable toxicity or up to 8 cycles. BRCA1/2 mutation status and immunohistochemical basal markers were included in the correlative studies. Sixty-four patients with the median age of 49 years were enrolled. Thirty patients (46.9%) had ≤1 year from diagnosis to recurrence. The median progression free survival (PFS) was 7.2 months (95%CI, 5.6-8.9 months) and overall survival (OS) was 19.1 months (95%CI, 12.4-25.8 months) with median follow-up 42 months. Patients received treatment for a median of six cycles. The overall response rate was 62.5%. The most common grades 3/4 toxicities were neutropenia (42.2%), thrombocytopenia (29.7%), anemia (18.8%) and nausea/vomiting (15.6%).No specific BRCA1/2 mutation carriers were identified. The efficacy of responses and basal-like subtype were independent favorable factors for PFS and OS, respectively. We conclude that the combination of GP has significant activity and a favorable safety profile as the first-line chemotherapy in mTNBC patients, in particular patients with basal-like subtype. The promising role of this combination as the front-line treatment for mTNBC continued to be evaluated in our ongoing phase III trial (CBCSG006).